GB1174059A - Quick Service Device on Automatic Compressed-Air Brakes - Google Patents

Abstract

1,174,059. Fluid-pressure brakes. OERLIKON-BUHRLE HOLDING A.G. 22 Dec., 1966 [24 Dec., 1965], No. 57513/66. Heading F2F. In a quick-service device on automatic compressed-air brakes, particularly for railway vehicles, a vent valve 30 comprises a valve body 32 to which is secured a piston 34 and an actuating member 1, acting through a disengageable intermediate member in the form of a two-armed lever 10, is adapted to open the vent valve 30 to connect a first chamber 38 connected to the train pipe 6a through the vent valve 30 and vented to atmosphere through a choke bore 40, a second chamber 37 mounted in the interior of the first chamber 38 being separated from the second chamber by the piston 34 such that when compressed air is in the first chamber 38, the piston 34 opens the vent valve 30 while compressed air in the second chamber 37 acts on the piston to close the vent valve. In the diagram, the apparatus is shown in the brake release position wherein air in the control reservoir 7a equals pressure in the train pipe 6a and a lower piston 2 is in its bottom position wherein the two-armed lever 10 is in the position shown under the influence of the spring 11 such that the lefthand prong 13 is just out of contact with a guide rod 14 and the vent valve 30 is closed under the action of the spring 41 so that the two chambers 37 and 38 are vented to atmosphere. An interrupter piston 16 is urged by the other prong 15 of the fork to the right as shown in the figure such that atmospheric air pressure prevails in the chambers 22, 24 and 27. When braking occurs, the pressure in the train pipe 6a is reduced and consequently the air pressure in the chamber 6 above the piston 2 of the actuating member 1 is lower than the air pressure in the chamber 5 so that the piston 2 rises to urge the prong 13 against the guide rod 14 and lift the vent valve 30 off its seat. Air from the train pipe then flows out of the chamber 6 into the chamber 38 of the quick service chamber 29 and escapes through the choke 40 to atmosphere. Air pressure also holds the valve 30 open by acting on the diaphragm 35 and also passes through the passage 28 into the chamber 27 to actuate the diaphragm 19 and cause displacement of the piston 16 towards the left so that the prong 13 comes out of engagement with the guide rod 14. This action initiates pressure in the brake cylinder 26 to apply the brakes. And the piston 16 remains in the left-hand end position until the brakes are released. The brake cylinder 26 is in communication with a control valve (not shown) through a pipe 25a.